Secretary of State Condoleezza Rice warned Iran on Thursday that the United States will not back down in the face of Iranian threats against Israel.

Iranian officials have strongly suggested the country's missile test on Wednesday was itself a warning to Israel not to attack Iran's nuclear facilities. Israel has left that option open.

"We are sending a message to Iran that we will defend American interests and the interests of our allies," Rice said at the close of a three-day Eastern European trip.

Rice noted U.S. efforts to increase its own security presence in the Persian Gulf and the defense capabilities of U.S. allies there.

• Click here to view photos of the Iranian missile test launch

VIDEO: Missile Test | Obama Calls Iran 'Great Threat'

"We take very very strongly our obligations to help our allies defend themselves and no one should be confused about that," she said.

Rice tied the latest Iranian missile test and rhetoric to U.S. plans for a future missile shield, which would theoretically protect Eastern Europe from missiles launched from Iran.

The system would place radar interceptors in the Czech Republic, a former Soviet satellite, and missiles in Poland. That has drawn protests from Russia, who says that's uncomfortably close.

Such a missile defense system "will make it more difficult for Iran to threaten and ... say terrible things, because their missiles won't work," Rice said.

Rice's trip to Eastern Europe highlighted the troubled U.S. relationship with Russia. Rice's visit began with a celebration of U.S plans to base anti-missile defenses in countries once under the Soviet hand, and a warning from Russia that it may respond with unspecified military action. It ended with a public display of close U.S. ties to Georgian President Mikhail Saakashvili, a Russian nemesis.

Georgia's relations with Russia have deteriorated since Saakashvili came to power in 2004. Saakashvili is pushing for Georgia's integration into the West and its NATO military alliance; Moscow sees Georgia as part of its sphere of influence.

Appearing at a news conference with Rice, Saakashvili thanked the U.S. for its support of Georgia's territorial integrity and criticized Russia for conducting what he called a "post Cold War land grab." He joked about an incident earlier this week in which Russian planes allegedly flew near the Georgian capital.

"It looks like some people have not noticed that the Cold War is over," he said.

Rice said Russia had a responsibility to restore stability in Georgia and that Russia should "behave in that way — resolving and solving the problem and not contributing to it."

Earlier, Rice met with Georgian opposition politicians and social activists, telling them the United States supported Georgia's struggles for democracy and pluralism following flawed elections won earlier this year by Saakashvili, the U.S.-backed president.

Rice had all but dared Moscow to critique her visit to this former Soviet republic locked in a shoving match with Russia that has seen Russia close its border with Georgia and impose trade and other restrictions.

Georgia has long accused Russia of aiming to annex Abkhazia and another separatist Georgian region, South Ossetia. Both have been outside the Georgian government's control since the end of separatist wars in the mid-1990s.

Russia does not formally recognize either region's separatist government, but it maintains close contacts with them and has granted passports to most of the regions' residents. Russia has peacekeeping forces in both regions; Georgia accuses the Russian forces of supporting the separatists.

Moscow recently sent in additional forces, a move Saakashvili denounced as "aggression."

"It is very important that all parties reject violence as an option. There must be a peaceful resolution and that's what we'll work for," Rice said, speaking with Saakashvili outside the president's future headquarters. The partly-built structure was draped with a three-story drapery painted to resemble the design of the finished building.

Georgia has said it suspects Russia of using peacekeeping troops as a cover to bring artillery and other heavy weapons into Abkhazia, and has flown pilotless reconnaissance drones over the breakaway region.

Georgia accused Russia of shooting down a spy drone earlier this year, which Russia denied. U.N. observers studied video footage and concluded that a Russian fighter did shoot down the drone.

The Abkhazia dispute was a chief reason for Rice's visit. U.S. officials say Georgia is not blameless but that Russia has helped make the situation truly dangerous.

Russia's president, Dmitry Medvedev, met with President Bush during the Group of Eight summit in Japan this week and told him that Russia would like "to normalize our relations with Georgia, but so far we do not see sufficient will" on the part of the Georgian leadership, aide Sergei Prikhodko said.